Six Nations 2015: Jonathan Davies warns of Jonathan Sexton threat

Jonathan Sexton and Jonathan Davies play their club rugby in France

The inclusion of fly-half Jonathan Sexton will be crucial for Ireland in the Six Nations on Saturday, Wales centre Jonathan Davies said before the sides meet at the Millennium Stadium.

Sexton has been troubled by a hamstring injury but Ireland are confident he will be fit to play in Cardiff.

Davies played alongside Sexton in all three Tests for the British and Irish Lions against Australia in 2013.

"He is obviously their general and marshals their troops," Davies said.

"I noticed that in Australia. He expected high standards at training.

"He knew his role and expected everyone else to know them. If you didn't, he gave you an earful.

"That's what professional rugby is about. He is one of the best in the world at the moment at marshalling the game."

Racing Metro's Sexton, 29, limped out of the latter stages of Ireland's 19-9 victory over England in Dublin on 1 March and has been battling to recover ever since.

Davies and midfield partner Jamie Roberts are set to be included in what will probably be an unchanged line-up following the 20-13 victory over France on 28 February.

Jonathan Davies scored Wales' second try in the victory in Scotland

Head coach Warren Gatland will name his team on Tuesday (11:00 GMT) for Saturday's game and Davies is expecting a tough test against Joe Schmidt's side.

Wales have only beaten Ireland on two occasions in Cardiff since 1983 and are up against a side defence coach Shaun Edwards described as the "best in Europe".

"Ireland are third in the world and they have won 10 games in a row," Davies said.

"They are a very good team, they are defending champions and are well-coached.

"It's a tough task for us, and we have to make sure we get a good week's preparation and really focus on the game."

Davies and Roberts previously faced the Irish centre combination of the now-retired Brian O'Driscoll and Gordon D'Arcy, omitted from Schmidt's training squad.

This time it will be a new unit of Jared Payne and Robbie Henshaw facing them.

"Their centre partnership is a good one," Davies said. "They are big boots to fill and they seem to be doing quite well.

"They have played well together and seem to have a good understanding, which is important for a centre pairing.

"They understand their roles and what each other is doing. That normally takes a bit of time, but they seem to have taken to it really quickly."